1. Technical Field
The present invention relates to a vacuum pump control device.
2. Background Art
A vacuum pump used for vacuum exhausting in an external device such as a semiconductor manufacturing device includes a pump main body and a control device configured to control the pump main body. The control device is cooled with refrigerant such as coolant water. Normally, the control device has a semi-closed structure, and a dew-point temperature in the control device is the same as a temperature outside the control device, i.e., an external temperature. Thus, when the control device is cooled with refrigerant, the inside of the control device locally has a temperature lower than the dew-point temperature, and dew condensation might be caused.
Patent Literature 1 (JP-A-2014-43827) has proposed a vacuum pump configured as follows: a first temperature detection unit is provided at a low-temperature portion in the control device, a second temperature detection unit and a humidity detection unit are provided at a high-temperature portion in the control device, and operation of a cooling device is controlled based on the relative humidity of the low-temperature portion calculated using information detected by each detection unit.
However, in a technique of Patent Literature 1, there is a problem that a dew condensation state cannot be properly determined when erroneous detection is made in any one of the three detection units (sensors).